Hello guys, i am new to this forum, and i need some urgent help, i used to run for like 3 hours
, and now i can’t even pass 7 mins without felling so tired in my leg muscles, it just gets tired so freaking fast, i stopped running for awhile and gain some weight, is that might be the reason?

Yes, it might.

WOW!!!! That's a pretty huge difference 3hrs-7mins. I would suggest building up your leg muscles by doing leg presses, leg extensions, and squats. You should also continue running. You will improve.

HA!

if you have ever run anythign like 90 minutes let alone 3 hours you know more about running that most all of us here.

joke post.

just a guess.

or you are exagerating your tail off. In that case, tell us your age, weight, and conditions so we can help.